# include <stdio.h>
# include <stdlib.h>
# include <string.h>
# define  MAX_COLS  20
# define  MAX_INPUT 1000

int  read_column_numbers( int columns[], int max );
void rearrange(char *output, char const *input, 
     int n_columns, int const columns[] );

     int main(void){
       int  n_columns;
       int  columns[MAX_COLS];
       char input[MAX_INPUT];
       char output[MAX_INPUT];

       while( gets( input ) != NULL ){
         printf( "Original input : %s\n", input);
         rearrange( output, input, n_columns, columns );
         printf( "Rearranged line: %s\n", output );
       }
       return EXIT_SUCCESS;
     }

int  read_column_numbers( int columns[], int max ){
  int num = 0;
  int ch;
  while( num < max && scanf( "%d", &columns[num] ) == 1 
      && columns[num] >= 0 )
      num += 1;
  if( num % 2 != 0 ){
    puts( "Last column number is not paired.");
    exit( EXIT_FAILURE );
  }
  while( (ch = getchar()) != EOF && ch != '\n' )
        ;

  return num;
}

void rearrange(char *output, char const *input, 
     int n_columns, int const columns[] ){
       int col;
       int output_col;
       int len;

       len = strlen( input );
       output_col = 0;

       for( col = 0; col < n_columns; col += 2 ){
          int nchars = columns[col + 1] - columns[col] + 1;
            if ( columns[col] >= len ||
              output_col == MAX_INPUT - 1 )
            break;
            if ( output_col + nchars > MAX_INPUT - 1 )
              nchars = MAX_INPUT - output_col - 1;
            strncpy( output_col + output_col, input + columns[col],
                  nchars );
            output_col += nchars;
            output[output_col] = '\0';
       }

     }